CO2STORAGE ATLAS. Norway NORWEGIAN NORTH SEA

Transcription

1 CO2STORAGE Norway ATLAS NORWEGIAN NORTH SEA

2 Introduction The CO2 Storage Atlas of the Norwegian part of the North Sea has been prepared by the Norwegian Petroleum Directorate, on request by the Ministry of Petroleum and Energy. One of the key objectives for this atlas is to provide input on where it is possible to implement safe long-term storage of CO2, and how much capacity there is for geological storage of CO2. This study is based on detailed work on all relevant geological formations and hydrocarbon fields in the Norwegian part of the North Sea. The work is based on several studies as well as data from more than 40 years of petroleum activity in the North Sea basin. 21 geological formations have been individually assessed, and grouped into saline aquifers. The aquifers were evaluated with regard to reservoir quality and presence of relevant sealing formations. Those aquifers that may have a relevant storage potential in terms of depth, capacity and injectivity have been considered. Structural maps and thickness maps of the aquifers are presented in the atlas, and were used to calculate pore volumes. Several structural closures have been identified, some were further assessed. A new geological study of the largest aquifer in the Norwegian sector of the North Sea, the Utsira-Skade aquifer, is included. A study of the CO2 storage potential in the Frigg field is provided, together with a summary of the CO2 storage potential in abandoned oil and gas fields. CO2 storage in enhanced oil recovery projects is also discussed. The methodology applied for estimating storage capacity is based on previous assessments, but the storage efficiency factor has been assessed individually for each aquifer based on simplified reservoir simulation cases. The assessed aquifers have been ranked according to guidelines which have been developed for this study. This atlas is based on large amount of data from seismic, exploration and production wells, together with production data. This data base is essential for the evaluation and documentation of geological storage prospectivity. We hope that this study will fulfil the objective that the information can be useful for future exploration for CO2 storage sites. We have not attempted to assess the uncertainty range in the atlas, but we have made an effort to document the methods and main assumptions. The assessments described in this atlas will be accompanied by a GIS data base (geographical information system). This will be published on the NPD web site spring 2012.

3 Geological provinces of the North Sea Møre Basin 62 East Shetland Basin East Shetland Platform Viking Graben Tampen Spur Horda Platform Sogn Graben Stord Basin Øygarden Fault complex Bergen Oslo Utsira High Stavanger Sele High Åsta Graben Egersund Basin Stavanger Platform Farsund Basin Central Graben Sørvestlandet High Fjerritslev Fault complex 57 Norwegian-Danish Basin

4 Characterization of saline aquifers Aquifers and structures have been evaluated in terms of capacity and safe storage of CO2. Reservoir quality depends on the calculated volume and communicating volumes as well as the reservoir injectivity. Sealing quality is based on evaluation of the sealing layers (shales) and possible fracturing of the seal. Existing wells through the aquifers/structures and seals have also been evaluated. Parameters used in the characterization process are based on data and experience from the petroleum activity on the NCS and the fact that CO2 should be stored in the supercritical phase to have the most efficient and safest storage. Each of the criteria in the table below is given a score together with a description of the data coverage (good, limited or poor). The score for each criteria is based on a detailed evaluation of each aquifer/structure. A checklist for reservoir properties has been developed. This list gives a detailed overview of the important parameters regarding the quality of the reservoir. Important elements when evaluating the reservoir properties are aquifer structuring, traps, the thickness and permeability of the reservoir. A corresponding checklist has been developed for the sealing properties. Evaluation of faults and fractures through the seal, in addition to old wells, are important for the sealing quality. An extensive database has been available for this evaluation. Nevertheless some areas have limited seismic coverage and no well information. The data coverage is colour-coded to illustrate the data available for each aquifer/structure.

5 Storage maturation and capacities Based on injection history Development of injection site Injection Suitable for long term storage 1,1 Gt Effective and safe storage Exploration Theoretical volume 43 Gt + 24 Gt (fields) Cut off criteria on volume/conflict of interest Volume calculated on average porosity and thickness 4 Gt INCREASED TECHNICAL MATURITY The evaluation of geological volumes suitable for injecting and storing CO 2 can be viewed as a step-wise approximation, as shown in the maturation pyramid. Data and experience from over 40 years in the petroleum industry will contribute in the process of finding storage volumes as high up as possible in the pyramid. Step 4 is the phase when CO 2 is injected in the reservoir. Throughout the injection period, the injection history is closely evaluated and the experience gained provides further guidance on the reservoirs ability and capacity to store CO 2. Step 3 refers to storage volumes where trap, reservoir and seal have been mapped and evaluated in terms of regulatory and technical criteria to ensure safe and effective storage. Step 2 is the storage volume calculated when areas with possible conflicts of interest with the petroleum industry have been removed. Only aquifers and prospects of reasonable size and quality are evaluated. Evaluation is based on relevant available data. Step 1 is the volume calculated on average porosity and thickness. This is done in a screening phase that identifies possible aquifers suitable for storage of CO 2. The theoretical volume is based on depositional environment, diagenesis, bulk volume from area and thickness, average porosity, permeability and net/ gross values.

6 Lithostratigraphic chart of the North Sea Group System Series Stage Southern North sea Norwegian- Danish Basin Southern Viking Graben Tampen Spur Horda Platform Nordland Hordaland Mississipian Rogaland Shetland Cromer Knoll Brent/ Viking/Tyne/ Dunlin Fladen Boknfjord Vestland JURASSIC Statfjord fm Hegre Zechstein equ Rotiegend equ NEOGENE PALAEOGENE CRETACEOUS TRIASSIC PERMIAN CARBONIFEROUS Pal Eoc Olig Mio Plio Plei Holo Cisurlian Pia Zan Mess - Aquit Chat Rup Pria - Ypres Than - Dan Maast Camp Sant U Coni Tur Cen Alb Apt Barr L Haut Valang Berr Mandal Tith Farsund U Kimm Oxf Haugesund Call Bath M Bajoc Aalen Toarc Plienc L Sinem Hett Rhæt U Nor Carn Ladin M Anis Olenek L Induan Lopingian Wuchi Changhsi - Guadalupian Roadian Capitan - Kung Artin Sakm Assel Pennsylvanian Gzel Kasim Moscov Bash Serpuk Vise Tour Sauda/ Flekkefjord Fm Draupne Fm Tau Fm Draupne Sognefjord Egersund Fm Fm Heather Heather Sandnes Fm Hugin Fm Fensfjord Fm Tarbert Krossfj. Ness Ness Bryne Fm Sleipner Fm Etive Oseberg Fm Drake Drake Fm Cook Cook Fm Amundsen/Burton Amundsen Fm Johansen Gassum Fm Statfjord? Statfjord Fm???? Utsira Skade Uplifted area Clastic continental deposits, unspecified Clastic continental deposits, mainly sandstone Clastic continental deposits, mainly shale and siltstone Salt (halite) Shallow-marine carbonate deposits Deep-marine carbonate deposits Volcanic deposits Calcareous shales Marginal evaporite deposits, sabkha Coastal, deltaic and flood-plain deposits Marine deposits, mainly sandstone Shallow-marine deposits, mainly shale Deep-marine deposits, mainly shale Clastics intermixed in carbonates, sandstone in shale Spiculite

7 Norwegian North Sea Aquifers Mapped geological formations and corresponding saline aquiferes Triassic Jurassic Cretaceous Paleogene Neogene Age Age Pliocene Miocene Oligocene Eocene Paleocene Late Early Late Middle Early Late Middle Piacenzian Zanclean Messinian Tortonian Serravallian Langhian Burdigalian Aquitanian Chattian Rupelian Priabonian Bartonian Lutetian Ypresian Thanetian Selandian Danian Maastrichtian Campanian Santonian Coniacian Turonian Cenomanian Albian Aptian Barremian Hauterivian Valanginian Berriasian Tithonian Kimmeridgian Oxfordian Toarcian Pliensbachian Sinemurian Hettangian Rhaetian Norian Carnian Ladinian s & Groups s & Groups Utsira Fm. Skade Fm. Grid Fm. Frigg Fm. Balder Fm. Fiskebank Fm. Draupne Fm. Sognefjord Fm. Johansen Fm. Cook Fm. Statfjord Fm. Ve Mb. Ula Fm. Ekofisk Fm. Tor Fm. Hod Fm. Boknfjord Fm. Callovian Fensfjord Fm. Krossfjord Fm. Hugin Fm. Bathonian Sandnes Fm. Bajocian Sleipner Fm. Brent Gp. Bryne Fm. Aalenian Gassum Fm. Skagerrak Fm. s not evaluated Evaluated Aquifers Evaluated Aquifers Utsira and Skade s Frigg Field Abandoned Gas Field Fiskebank Fm. Stord Basin Jurassic Model Stord Basin Mounds * Sognefjord Delta East Hugin East Bryne / Sandnes s South * Bryne / Sandnes s Farsund Basin Johansen and Cook s * Statfjord Fm. Gassum Fm. * Evaluated prospects

8 Saline aquifers Definition and principles for selection of storage sites An aquifer is a body of porous and permeable sedimentary rocks where the water in the pore space is in communication throughout. Aquifers may consist of several sedimentary formations and cover large areas. They may be somewhat segmented by faults and by low permeable layers acting as baffles to fluid flow. Maps, profiles and pore pressure data have been utilized in order to define the main aquifers. All the identified aquifers in the area of this atlas are saline, most of them have salinities in the order of sea water or higher. Skagerrak Fm Gassum Fm Statfjord Fm East Bryne Fm Sandnes Fm Aquifer Permeable formations Group Fiskebank Fm Contourite in the Stord Basin Mounds in the Stord Basin The Sognefjord Delta Utsira and Skade s The Frigg and Heimdal Field Aquifer Conceptual sketch showing location of aquifers relative to depositional systems

9 Aquifers in the hydrocarbon provinces are treated separately In the western provinces, west of the red line in the lower middle figure, Paleogene and older aquifers contain hydrocarbons. East of the line, discoveries have only been made in local basins where the Jurassic source rock has been buried to a sufficiently high temperature to generate hydrocarbons. In the eastern area, all the large aquifers have been selected based on the established criteria and storage capacity is estimated by the method described in the atlas. In the petroleum provinces, it is considered that exploration and production activities will continue for many years to come. The most realistic sites of CO2 storage will be some of the abandoned fields, in particular the gas fields. Consequently, an indication of the storage capacity of the fields has been given, but no aquifer volumes have been calculated. Some of the oil fields are considered to have a potential for use of CO2 to enhanced oil recovery. Some of the CO2 used for EOR will remain trapped. The capacity for this type of CO2 trapping has not been calculated Approximate limit for significant hydrocarbon migration Heimdal Fm Sognefjord Fm Ula Fm Bryne Fm Brent Gp Oil Gas 61 Oil Gas Oil w/gas Gas/Condensate Statfjord Fm Medium overpressure Weak overpressure Highly overpressured Oil w/gas 61 Gullfaks Gas/Condensate 60 Troll Ekofisk Distribution of major aquifers at the Jurassic levels relative to the petroleum provinces Some aquifers occur in both provinces 7 8

10 Distribution of evaluated aquifers Depth to the top Jurassic 300 m 62 Depth to the mid Jurassic 270 m m Faults Sognefjord Fm Hugin Fm (east) Hugin Fm (west) Sognefjord equivalent Sandnes Fm m Brent Gp Bryne Fm Sleipner Fm Faults Jæren graben Contour interval 200 m 61 Ula Fm Contour interval 200 m

11 The Utsira and Skade aquifer Top of Skade. The white polygon indicates area which may be favorable for CO 2 storage. Red dot shows Sleipner injection area. The grid squares are 20 km x 20 km. Top of Utsira. The black polygons indicate areas which may be favorable for CO 2 storage. Storage of CO 2 in abandoned fields Structural map of the Frigg field with all wells

12 Professor Olav Hanssens vei 10 Postboks 600, NO-4003 Stavanger Norway For more information and purchase of the CO 2 storage atlas: Trykk: Kai Hansen, Stavanger